DE69526692T2 - Process cartridge and imaging device - Google Patents

Description

FIELD OF THE INVENTION AND STATE OF THE ART

The present invention relates to a process cartridge and an image forming apparatus in which such a process cartridge is used.

In this case, the image-producing device includes an electrophotographic copier, an electrophotographic printing device (e.g. LED printer, laser printer), an electrophotographic fax machine, an electrophotographic word processor and similar devices.

The term process cartridge in this case means a cartridge which is equipped with an electrophotographic photosensitive element, a charging device, a developing device and a cleaning device as a unit and is detachably attached to the main assembly of an image forming apparatus. The said unit can also be composed of an electrophotographic photosensitive element and at least one of the said devices, i.e. the charging device, the developing device and the cleaning device, or of a developing device and an electrophotographic photoelectric element.

An image forming device is known which operates according to an electrophotographic process and is equipped with a process cartridge. The advantage of such a combination is that maintenance can be carried out by the user himself without The service can be carried out by calling in an expert, thereby improving the operational readiness of the device. This type of device is used worldwide.

A process cartridge improves the insertion and removal of the device main assembly.

Document JP-A-05297649 describes a process cartridge for an electrophotographic image forming apparatus, which has four projections arranged in pairs for engaging in guide elements of the image forming apparatus.

Document EP-A-0560618 discloses a process cartridge for an image forming apparatus which has longer projections as guides for insertion into and removal from the image forming apparatus. This cartridge is also provided with a pivoting knob by which it can be more easily removed from the apparatus.

Document EP-A-520802 discloses an image forming apparatus which is provided with a guide in the form of a recess for receiving the projections present on a process cartridge.

US patents 4,873,548 and 5,047,803 describe some improvements in cartridge mounting.

According to US Patent 4,873,548, a first frame is provided with a positioning element and the process cartridge is inserted into a second frame in such a way that when the frame is closed, the positioning element causes the process cartridge to be positioned.

According to US Patent 5,047,803, when a corresponding element is pivoted to expose and close an opening, a force is exerted on the process cartridge in order to make it easier to remove it from the imaging device.

All of these improvements are designed to make it easier to insert or remove a process cartridge. However, further improvements are being sought.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a process cartridge and an image forming apparatus in which such a process cartridge can be accurately positioned.

Another object of the present invention is to provide a process cartridge and an image forming apparatus in which the insertion and removal of such a process cartridge can be carried out in a simple manner.

Still another object of the present invention is to provide a developing frame in which toner can be effectively accommodated, a process cartridge provided with such a developing frame, and an image forming apparatus in which such a process cartridge is used.

According to one aspect of the present invention, there is provided a process cartridge which can be detachably attached to the main assembly of an image forming apparatus and which comprises:

An electrophotographic photosensitive member having a first and a second axial end, a processing device acting on the photosensitive element,

a first projection for positioning the process cartridge when inserted into the device main assembly, the first projection extending outwardly from a first frame portion provided at the first axial end of the photosensitive member,

a second projection as a pivot point when removing the process cartridge from the main assembly, the second projection extending outward from the first frame portion,

a third projection for positioning the process cartridge when inserted into the device main assembly, the third projection extending outwardly from a second frame portion provided at the second axial end of the photosensitive member,

a fourth projection as a pivot point when removing the process cartridge from the main assembly, the fourth projection extending outwardly from the second frame portion, and

a knob disposed above a connecting line between the center of the first projection and the center of the second projection as viewed from an axial end of the photosensitive member, for pivoting the process cartridge about an axis defined by the second and fourth projections when removed from the apparatus main assembly, and for canceling the positioning action of the first and third projections.

In a second aspect of the present invention, there is provided a combination of a process cartridge and an apparatus for forming an image on a recording medium according to claim 18.

These and other objects, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a sectional view of an image forming device equipped with a process cartridge.

Fig. 2 shows a sectional view of a process cartridge.

Fig. 3 shows a process cartridge in perspective.

Fig. 4 shows an example of how the cover of the image forming device is lifted and the process cartridge is inserted into the device.

Fig. 5 shows a sectional view of a developing device.

Fig. 6 shows a perspective view of the frame and wall elements of the developing device as individual elements.

Fig. 7 shows in perspective how the wall elements and the frame of the developing device are connected to each other.

Fig. 8 shows a cover in perspective.

Fig. 9(a) shows the top view and Fig. 9(b) the side view of the cover seen in the longitudinal direction.

Fig. 10 shows the sectional view of the cover in the swung-out position.

Fig. 11 shows the swung-out cover in perspective.

Fig. 12 shows the side view of the process cartridge.

Fig. 13 shows the sectional view of the device section, which serves as a guide when inserting the process cartridge.

Fig. 14 shows an example of the removal of the process cartridge from the image forming device, with the first projection resting in a recess.

Fig. 15 shows an example of the removal of the process cartridge from the image forming device, whereby the process cartridge is pivoted around the second projection by pulling on a knob.

Fig. 16 shows an example of removing the process cartridge from the image forming device by pulling on the knob.

Fig. 17 shows a sectional view of another type of process cartridge in which the knob is not located at the top.

Fig. 18 shows the sectional view of another embodiment of the developing device which has a seal holding section.

Fig. 19 shows the sectional view of another embodiment of the developing device in which the wall is provided with a hinge.

Fig. 20 shows the sectional view of another embodiment of the cover, in which the first and the second section are connected to each other by a connecting element.

Fig. 21 shows the sectional view of another type process cartridge in accordance with the present invention.

Fig. 22(a) shows the left side view of the cleaner frame of the process cartridge shown in Fig. 21 and Fig. 22(b) shows the right side view of the same.

Fig. 23 shows an example of the insertion of the process cartridge shown in Fig. 21 into the main assembly of the image forming device and the removal of the cartridge therefrom.

Fig. 24 shows an example of the moment at which the process cartridge shown in Fig. 21 snaps into the main device assembly.

Fig. 25 shows an example of the moment at which the process cartridge shown in Fig. 21 is pressed out of the main device assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first preferred embodiment is described in conjunction with Figs. 1 to 16, the description of further embodiments is given in conjunction with Figs. 18 to 20 and 21 to 25.

Embodiment 1

In the first embodiment, (1) the general structure of the image forming apparatus and the process cartridge, (2) the frame of the developing device, (3) the cover, and (4) the installation and removal of the process cartridge are described.

(General structure)

The overall structure of the electrophotographic image forming device and the process cartridge is described below in conjunction with Figs. 1 to 4. Fig. 1 shows the sectional view of the entire electrophotographic image forming device with the process cartridge inserted. Fig. 2 shows the sectional view of the process cartridge and Fig. 3 shows the process cartridge in perspective. Fig. 4 shows an example of how the cover of the image forming device is lifted and the process cartridge is inserted into the device main assembly.

With the electrophotographic image forming apparatus A shown in Fig. 1, an image is formed on a recording medium in an electrophotographic process. A toner image is first formed on a drum-shaped electrophotographically sensitive element (hereinafter referred to as a photosensitive drum) as an image carrier element. In synchronization with the image formation, a recording medium 2 is taken from a feed tray 3a by a transport device 3, which has a pickup roller 3b, a transport roller 3c and other elements, and fed to the photosensitive drum. Then, the transfer roller 4 as a transfer device is supplied with current and thereby the toner image formed on the photosensitive drum of the process cartridge is transferred to the recording medium 2. The recording medium provided with the toner image is fed to a The toner is fed to the fixing device 5. The fixing device 5, which has a drive roller 5a and a fixing roller 5b equipped with a heating device, transfers heat and pressure to the recording medium 2 passing through it and in the process fixes the transferred toner image. Finally, the recording medium 2 provided with the fixed toner image is transported further, deflected by discharge rollers 3e and 3f and pushed onto a tray 6.

The surface of the photosensitive drum 7 in the process cartridge B, which is provided with a photosensitive layer and serves as an image carrier element, is evenly charged via a charging roller 8 supplied with a voltage while the drum is rotating. A laser beam carrying the image data is then projected from an optical system 1 through an exposure opening 9 onto the photosensitive drum 7, thereby creating a latent image on the drum. The latent image is developed by a developing device 10 using toner.

The charging roller 8 is brought into contact with the photosensitive drum 7 to charge it. In the developing device 10, toner is applied to the areas of the photosensitive drum 7 to be developed, thereby developing the latent image formed on the photosensitive drum 7. The optical system has a laser diode 1a, a polygon mirror 1b, an objective lens 1c and a full reflection mirror 1d.

In the developing device 10, the toner stored in a toner chamber 10a is fed to a developing chamber 10b and by rotating a developing roller 10c arranged in the developing chamber and provided with a magnet, a triboelectrically charged toner layer is produced on the developing roller 10c by a developing blade 10d. From this toner layer Toner is applied to the area of the photosensitive drum 7 to be developed. By transferring toner to the photosensitive drum 7 in accordance with the latent image, the latter is made visible. In other words, a toner image is formed on the photosensitive drum 7.

The transfer roller 4 is supplied with current whose polarity is opposite to that of the toner image, thereby transferring the toner image present on the photosensitive drum 7 to the recording medium 2. The residual toner remaining on the photosensitive drum 7 is removed by a cleaning device 11. The cleaning device 11 has an elastic cleaning blade 11a, which scrapes the residual toner from the photosensitive drum 7 and pushes it into a toner waste container 11b.

In the cartridge composed of a developing frame 12, a developing wall 13 and a cleaning frame, some other components are arranged besides the photosensitive drum 7. More specifically, the developing frame 12 and the developing wall 13 are welded together to make the toner chamber 10a and the developing chamber 10b, and the developing roller 10c and the developing blade 10d are inserted into the developing chamber 10b. The photosensitive drum 7, the charging roller 8 and the cleaning device 11 composed of various elements are attached to the cleaning frame 14. Finally, the developing frame 12 and the cleaning frame 14 are pivotally joined to each other to complete the process cartridge B.

The process cartridge B has an exposure opening 9, which enables the irradiation of the photosensitive drum 7 with the light beam carrying the image data, and a transfer opening 15, which enables direct contact between the photosensitive drum 7 and the recording medium 2 and thereby ensures the transfer of the toner image present on the photosensitive drum 7 to the recording medium 2. The process cartridge B also has a cover 16 which exposes or closes the openings 9 and 15.

The image forming device A shown in Fig. 4 has a cover 18 which is attached to the device main assembly 17 and can be pivoted about an axis 19. When the cover 18 is pivoted away from the device main assembly, a guide element 20 (Fig. 13) is released, which guides the process cartridge B when it is inserted into the device main assembly. The insertion and removal of the process cartridge B is carried out by an operator along this guide 20.

(Structure of the development frame)

The structure of the frame forming a section of the developing device is described below in conjunction with Figs. 5 to 7. Fig. 5 shows the sectional view of the developing device, Fig. 6 shows a perspective view of the frame and the wall of the developing device separated from each other and Fig. 7 shows a perspective view of the assembly of the frame and wall of the developing device.

The developing device 10 shown in Figs. 5 and 6 has the toner chamber 10a and the developing chamber 10b, which are formed by joining the frame 12 and the wall 13 of the developing device.

The section 12b formed by the toner chamber 10a and the developing chamber 10b has a sealing section 12a with a toner supply opening 12a1 and a sealing section 12c with a toner supply opening 12c1 and is provided with a toner filling opening (not shown) on one end.

The wall 13 and the frame 12 of the developing device are connected to one another in such a way that the open side of the latter is covered. Integral components of the wall 13 are the wall sections 13a and 13b for covering the opening in the toner chamber section 10a and the opening in the developing chamber section 10b, respectively. At the transition from the wall section 13a to the wall section 13b, there is a recess 13a1.

The frame 12 and the wall 13 of the developing device 10 are made of synthetic resin by injection molding.

The above-mentioned components are assembled in the manner described below. First, the wall 13 is placed over the opening of the frame 12 and welded to the frame. In this embodiment, a fitting element 21 is added to both end faces to precisely connect the wall 13 to the frame 12.

Both end faces of the frame 12 are provided with holes 12b1 and 12b2 and both end faces of the wall 13 are provided with a hole 13c. On the fitting element 21 there are pins 21a which are pressed into the corresponding hole 12b1, 12b2 or 13c.

When the frame 12 and the wall 13 are connected to one another in this way, the gap between the frame 12 and the wall section 13a is closed by fusion welding, but the gap between the frame 12 and the wall section 13b is closed by pressure welding via a seal 22 made of polyurethane foam (Fig. 5) inserted between the two, this seal being intended to prevent the leakage of toner. Since If the joint with the seal 22 is not closed by fusion welding, this joint is not as strong as the joint between the frame 12 and the wall section 13a. Due to the pins 21a of the fitting element 21 pressed into the holes 12b1, 12b2 and 13c, this connection can be almost as strong as that achieved by fusion welding; even if a torsional force acts on the joint, no gap is formed at it, so that toner cannot leak out.

The fitting element 21 also fixes the positional relationship between the frame 12 and the developing roller 10c when assembling the same and acts as a positioning element when assembling the cleaning device 14 to the frame 12 welded to the wall 13.

When the frame 12 and the wall 13 are connected to one another in the manner described, the recess 13a1 on the wall 13 causes its lower end 13a and the longitudinal edge of the toner feed opening 12a1 (Fig. 5) to be approximately at the same height. Before the developing roller 10c and the developing blade 10d are inserted into the developing chamber 10a, a seal 17 is glued, welded or otherwise attached to the frame section 12a in order to seal the opening 12a1. After the above-mentioned components have been assembled to produce the developing device 10, toner T is filled into the toner chamber 10a through the above-mentioned toner filling opening and the filling opening is closed with a cap (not shown).

Then, the frame of the cleaning device 14 equipped with the photosensitive drum 7, the cleaning element 11 and other elements is attached to the frame 12 with the wall 13 welded to it and the assembly of the process cartridge B is completed.

As shown in Fig. 5, the frame 12 is shaped so that the toner chamber 10a is located above the development chamber 10b and a part of the toner chamber 10a extends slightly beyond the development chamber 10b in the direction of the photosensitive drum 7.

In this embodiment, the first frame (the frame member 12) has the following sections: a toner storage section (chamber section 12b) for storing the toner required for the developing process, an opening 12b1 in the toner storage section, and a toner supply opening 12a1 for supplying toner from the toner storage section to the developing station. The second frame member (the wall 13) has the following sections: a section 13d for attaching the developing roller 10c as a developing device, and a cover (wall section 13a) for closing the opening 12b1 of the toner storage section. The first and second frame members form the frame of the developing device. In other words, the frame of the developing device of this embodiment comprises: the first frame (the first frame member 12) having the toner storage section and a developing section (developing device mounting section 13d) for developing the latent image formed on the photosensitive drum 7 with the toner stored in the toner storage section, which extends from the toner section to the developing section (the section immediately adjacent to the developing station), and the second frame member (the wall 13) which extends from the developing section to the end of the toner storage section.

A developing blade 10d1 is attached to a specific location of the first frame to regulate the amount of toner adhering to the surface of the developing roller 10c mounted in the portion 13d of the second frame member. The lower portion 10a1 of the toner storage portion 10a in the first frame is inclined toward the toner supply opening 12a1 so that toner from the toner storage portion is supplied to the developing area without loss. The seal 27 for sealing the toner supply opening 12a1 prevents leakage of toner before the process cartridge B is inserted into the image forming apparatus. This seal must be removed by the operator before the process cartridge is inserted.

The cover portion of the second frame member (toner chamber wall 13a) has a portion 13a2 which is inclined toward the toner supply opening 12a1 after the first and second frame members are joined together. The lower end 13a3 of the inclined wall portion 13a2 and the edge of the toner supply opening 12a1 are substantially at the same level. That is, the toner stored in the toner storage portion can be supplied to the developing area without loss.

The first and second frame elements are joined together on the side on which the toner storage section is to be created, i.e. on the sides 12f and 13f. The joining can be carried out by fusion welding (e.g. ultrasonic welding), gluing, screwing, snapping or in some other way. To join the first and second frame elements together, a fitting element 21 is used on each end face of these two elements. The fitting elements are provided with holes into which the pins 21a present on the end faces of the two frame elements are pressed. At the section 13d as the mounting section for the developing device, a seal (which prevents the leakage of toner) 22 is inserted between the first and second frame elements.

The first and second frame elements are made of a plastic material (e.g. particularly impact-resistant styrene).

This allows the interior of the toner chamber 10a to be enlarged without enlarging the process cartridge B. Since the toner chamber section 10a of the frame 12 runs obliquely towards the discharge side, it can be manufactured from synthetic resin or a similar material by injection molding.

After peeling off the seal 27, the process cartridge B can be inserted so that toner passes from the toner chamber 10a to the developing chamber 10b by its own weight and no conveying element is required. When the process cartridge B is inserted in the image forming device A (the state shown in Fig. 5), the sealing section 12a extends obliquely to the right, and the recess 13a1 places the lower end of the toner chamber wall 13a and the right edge of the toner supply opening 12a1 almost at the same level so that no toner remains on the opposite side of the sealing section 12a.

As already mentioned, the preferred method for joining the frame 12 to the wall 13 is fusion welding, since this ensures a tight connection that prevents the leakage of toner. The frame can also be joined to the wall by gluing or another method, or by using small screws and nuts, as well as by using hooks or other elements, with a gasket placed between the two parts.

(Construction of the cover)

The structure of the cover is described below in conjunction with Fig. 8 to 11. Fig. 8 shows the cover in perspective. Fig. 9(a) shows the side view of the cover in the transverse direction and Fig. 9(b) the side view of the cover seen in the longitudinal direction. Fig. 10 shows the sectional view of the process cartridge with the cover swung out. Fig. 11 shows the process cartridge with the cover swung out in perspective.

An exposure opening 9 is provided in the upper frame part of the process cartridge B, and an opening 15 is provided in the lower frame part for transferring the toner image produced on the photosensitive drum 7 to the recording medium 2. These two openings 9 and 15 are exposed and covered by the cover 16. In this embodiment, which is described below, these two openings are formed by the frame of the developing device 12 and the frame of the cleaning device 14.

As shown in Figs. 8 and 9, the cover 16 has a first portion 16a extending over the exposure opening 9 and a second portion 16b extending over the transfer opening 15 as integral parts which cover or expose these two openings. These portions 16a and 16b prevent damage to the photosensitive drum 7, adhesion of foreign matter such as dust thereto, optical aging of the photosensitive material, etc.

As can be seen from Fig. 9(a) and 9(b), the cover 16 has a pivot pin 16c at both longitudinal ends. The first section 16a of the cover 16 extends diagonally downwards from the pivot pin 16c, while the second section 16b bridges two arms 16d, which extend from the two pivot pins 16c first in the opposite direction to the section 16a, then are angled downwards and finally to the right and follow the contour of the frame of the cleaning device 14.

As shown in Fig. 2, a U-shaped bearing point 14a is arranged on both sides in the upper section of the frame of the cleaning device 14. The respective pivot pin 16c of the cover 16 extends into these bearing points 14a; in other words, the cover 16 can be pivoted around the third frame, i.e. the frame of the cleaning device 14. A leg of a torsion spring 23 is pushed into one of the pivot pins 16c, so that the spring constantly exerts a force on the cover 16 and presses it in the direction of the two openings 9 and 15. The U-shaped bearing points 14a are narrower at the top than at the bottom and are elastically deformable in order to be able to easily press the pivot pins 15c into them and in this way to pivotally attach the cover 16 to the frame of the cleaning device. The elasticity of the U-shaped bearing points 14a also enables the pivot pins 16c to be easily pulled out of them.

A projection 16e is provided at a certain point on the arm 16d. When the process cartridge B is inserted into the image forming device, which will be discussed in more detail later, the projection 16e abuts against the stop 13a provided on the main assembly of the device A, whereby the cover 16 is pivoted about the pivot pins 16c. The first section 16a exposes the exposure opening 9 and the second section 16b exposes the transfer opening.

More specifically, the projection 16e is arranged laterally on one of the two arms 16d, extends axially to the photosensitive drum, slides along the stop 13a when the process cartridge is inserted and presses the cover 16 outwards to expose the two openings 9 and 15.

As already mentioned, the sections 16a and 16b, which expose and close the opening 9 and 15 respectively, are integral Components of the cover 16. This eliminates the need for a complicated hinge mechanism, reduces the number of individual cover parts and simplifies the assembly of the cover 16 while ensuring safe exposure and closing of the openings.

As shown in Fig. 11, the arm 16d is made of a thin plate and follows the outer contour of the frame of the cleaning device 14. The end section of this frame is provided with a recess 14a, the depth of which corresponds to the thickness of the arm 16d. In the closed state, the arm 16d lies in the recess 14b so that its outer surface and the outer surface of the frame of the cleaning device 14 are essentially flush with one another.

In the described configuration, the arm 16d does not protrude either laterally or outwardly beyond the frame of the cleaning device 14. This allows the length and the overall size of the process cartridge B to be reduced.

As shown in Fig. 1, when the process cartridge B of this embodiment is installed in the image forming apparatus A, the cover 16 is pivoted, thereby bringing the second portion 16b into a position above the fixing device 5. The fixing device provided with a heater generates heat, but an air passage formed between the second portion 16b and the frame of the cleaning device 14 allows the heat generated by the fixing device to be dissipated, thereby preventing the temperature of the apparatus from rising.

The cover 16 is provided with reinforcing ribs 16f on the arm section 16d at the sides and on the edges or near the edges of the sections 16a and 16b.

As already described, in this embodiment, the first and second sections 16a and 16b and the pivot pins 16c are integral parts of the cover 16. The pivot pins 16c serve as an axis about which the cover 16 is pivoted relative to the frame of the cleaning device 14 and as elements for fastening the cover 16 to the frame of the cleaning device 14. The second section 16b is connected to the respective pivot pin 16c via the arms 16d, the configuration of the arm 16d following the outer wall configuration of the process cartridge when the cover 16 is mounted on the frame of the cleaning device 14. Such an arm 16d is arranged at both longitudinal ends of the section 16b. The cover is made in one piece from synthetic resin (e.g. from highly impact-resistant styrene or a similar material), i.e. i.e., the first portion 16a, the second portion 16b, the pivot pins 16c, the arms 16d, the projection 16e and the ribs 16f are integral parts of the cover 16.

(Inserting and removing the process cartridge)

The following describes, in conjunction with Fig. 4 and 12-17, the insertion and removal of the process cartridge B into and from the image generation device A. Fig. 12 shows a side view of the process cartridge. Fig. 13 shows the sectional view of the image generation device, but especially the cartridge guide. Fig. 14-16 show examples of the removal of the process cartridge B from the device. Fig. 17 shows examples of the removal of the process cartridge B from the device, although the knob is not located at the top but at a different location.

In Figs. 14-16, the alphanumeric reference symbols P1 and P2 indicate the directions in which the process cartridge B is moved when it is inserted into or removed from the apparatus main assembly. In this embodiment, The process cartridge B is inserted or removed at right angles to the axis of the photosensitive drum 7, as shown in Fig. 4, with the developing device 40 of the cartridge being placed at the front and the cleaning device 14 at the rear.

As shown in Fig. 12, the process cartridge B has a first projection 24 and a second projection 25 on both end sides of the frame of the cleaning device 14, where the first-mentioned fixes the position of the process cartridge and the other ensures that the cartridge orientation is maintained. The first projection 24 is arranged directly in the direction of the axis of rotation of the photosensitive drum 7, the second projection 25 is arranged behind the first projection 24 with respect to the direction P1 as the cartridge insertion direction. An integral part of the frame of the cleaning device 14 is a knob 26. This knob is arranged above the line C-C as a connecting line between the center of the first and the wide projection 24 or 25.

The image forming apparatus A is provided with a cover 18 which is pivoted about the axis 19 to open and close the apparatus. When the cover 18 is pivoted out (Fig. 4), the space provided for the process cartridge in the apparatus main assembly is exposed with a guide 20 arranged on both end walls such as that shown in Fig. 13. This guide is provided with a groove 20a which extends diagonally downwards and serves as a guide for the process cartridge B and has a positioning recess 20b on the bottom.

As can be seen from Fig. 16, the operator grasps the knob 26 of the process cartridge and pushes the projection 24 on both ends of the cartridge into the respective groove 20a. When the process cartridge is pushed in further B into the image forming device, the projection 25 on both ends is also inserted into the respective groove 20a. From this moment on, the process cartridge 8 is guided by the four projections in the two grooves 20a. When the process cartridge reaches the lowest point, the two projections 24 touch the wall of the respective recess 20b, as shown in Fig. 15. The process cartridge B is now pivoted about the two projections 25 slightly in a clockwise direction (arrow direction a in Fig. 15). The first two projections 24 slide into the respective recess 20b and thereby fix the process cartridge in the device. Since the second two projections 25 remain in the respective groove 20a, the orientation of the process cartridge in the device is maintained. Since the process cartridge B is only slightly pivoted so that the first projections 24 can slide into the respective recesses 20b, the helical gear 7a arranged at one end of the photosensitive drum 7 and the helical gear 21 arranged on the main assembly of the device A, into which the helical gear 7a engages, are hardly damaged. Since the process cartridge B is pushed upwards when it is removed from the main assembly of the device A, the two helical gears can be easily brought out of engagement. The helical gear 21 transmits the driving force of a motor (not shown) arranged on the main assembly of the device to the photosensitive drum 7.

The following describes in detail the steps for removing the process cartridge B from the imaging device for replacement.

An attempt to simply pull the process cartridge out of the device A will not succeed, since the first two projections 24 rest in the respective recess 20b. Before the process cartridge can be removed from the device, the two first projections 24 are lifted out of the respective recess 20b.

More specifically, the operator pulls the knob 26 of the process cartridge B of this embodiment toward himself and swings the process cartridge B counterclockwise (arrow direction b in Fig. 15), whereby the two projections 24 slide out of the respective recess 20b. In other words, when the knob 26 is pulled in the arrow direction P2, as shown in Fig. 14, the component Px of the pulling force P2 acts on the two projections 24 and thereby generates a moment around the second projections 25, but at the same time the component Pxy of the force Px also acts on the two projections 24 and lifts them out of the recess 20b, as shown in Fig. 15. In this state, the knob 26 is pulled further in the direction of arrow P2 and, guided by the projections 24 and 25 in the respective groove 20a, the process cartridge B is pulled out of the device.

In other words, the operator only has to pull the knob 26 in the direction of the arrow P2 to pull the process cartridge B out of the image forming device A.

However, if the knob 26 is located below the line C-C as a connecting line between the center of the first projection 24 and that of the second projection 25, as shown in Fig. 17, and the operator pulls the knob 26 in the direction of arrow P2, the process cartridge B does not swing about the second projections 25, so that the first projections 24 do not slide out of the respective recess 20b. In this case, the process cartridge B can be removed from the device only if the knob 26 is first pushed down in the direction of arrow Q to lift the first projections 24 out of the respective recess 20b and then pulled in the direction of arrow P.

From these explanations, it is easy to see that in this embodiment, the arrangement of the knob 26 above the line C-C as a connecting line between the center of the first projection 24 and that of the second projection 25 is more advantageous because in order to remove the process cartridge B from the device, the operator only has to pull on the knob 26 in the cartridge removal direction.

By manufacturing the frame of the cleaning device 14 with the projections 24 and 25 and the knob 26 as integral components thereof, the accuracy of the positional relationship between the individual components can be improved and the loosening of the connection between the projections and the groove can be prevented even with a slight touch of the knob 26.

(Other embodiments)

Next, in conjunction with Figs. 18-20, further embodiments of the present invention will be described, which concern (1) frame of the developing device, (2) construction of the cover, (3) installation and removal of the cartridge, and (4) configuration of various other components, wherein those components which have the same function as those of the first embodiment are designated by the same reference numerals to avoid duplicate description.

(Other embodiments of the frame of the developing device)

In the first embodiment, when the frame 12 and the wall 13 are connected to each other, only the chamber wall 13a is fixed to the frame 12 by fusion welding and then a fitting element 21 is placed on each end face of this composite to fix the positional relationship between the two components 12 and 13 (see Fig. 7). However, it is also possible to completely join the frame 12 and the wall 13 together by fusion welding.

In such a design, the two components 12 and 13 are more firmly connected to one another, so that separation of the two is prevented when torsional forces occur. In this case, however, it is necessary to insert a seal at the joint between section 13b of the wall 13 and the frame 12 in order to prevent toner from escaping. This makes it possible to reduce the number of components and thus the number of assembly steps.

In the first embodiment, the sealing portion 12a is provided on the frame 12, to which a seal 27 is attached by gluing, fusion welding or in some other way in order to close the toner supply opening 12a1. However, the seal 27 can also simply be clamped, as shown in Fig. 18.

The frame 12 shown in Fig. 18 has a seal mounting portion 12a with the toner supply opening 12a1 similar to that of the first embodiment. In this embodiment, a seal clamping portion 28 is arranged on the wall 13 between the toner chamber wall 13a and the development chamber wall 13b, which seal clamping portion 28 abuts against the seal mounting portion 12a when the wall 13 is connected to the frame 12. The seal clamping portion 28 is provided with a toner supply opening 28a, the size and position of which correspond to those of the toner supply opening 12a1.

A toner retaining gasket 29 made of polyurethane foam or a similar material is placed between the frame 12 and the wall 13 and both are fastened with small screws Consequently, the seal 27 does not need to be secured by gluing, welding or other means and can be more easily removed before the cartridge is inserted, so that the frame 12 and the wall 13 can be recycled more easily because they are not contaminated by adhesive residues, welding residues or other foreign matter.

At the boundary portion between the toner chamber wall 13a and the developing chamber wall 13b, a hinge 31 may be arranged to access the seal clamping portion 28.

The construction shown in Fig. 19 differs from that shown in Fig. 18 in that a flexible joint 31 is arranged between the toner chamber wall 13a and the developing chamber wall 13b of the wall 13 and that when connecting the wall 13 to the frame 12, only the toner chamber wall 13a is fastened to the frame 12 by fusion welding, while at the connection point between the developing chamber wall 13b and the frame 12, a seal 32 made of polyurethane foam or another material placed between these two components ensures tightness.

In this case, after joining the toner chamber wall 13a of the wall 13 to the frame 12 by fusion welding, the developing chamber wall 13b may be bent back and the seal 27 may be clamped between the seal mounting portion 12a and the seal clamping portion 28.

In this construction with the joint 31 arranged on the wall 13, the position of the toner chamber wall 13a is fixed by deflection at this joint 31; in this case, however, it is necessary, after connecting the wall 13 to the frame 12, to place a fitting element 21 with positioning pins on both end faces of this assembly, as in the first embodiment. to maintain the angle of the joint 31.

So far, the frame structure of the developing device has been described with reference to that used in the process cartridge of the first embodiment, but such a structure is also possible in developing devices which have a toner chamber and a developing chamber and in the latter a developing roller, a developing blade and other elements are arranged, and can bring about the same effects.

(Other cover designs)

In the first embodiment described, the cover 16 is made in one piece, i.e. the first section 16a, which exposes and closes the exposure opening 9, and the second section 16b, which exposes and closes the transfer opening 15, are integral parts of the cover (Figs. 8 and 9). As Fig. 20 shows, these two sections 16a and 16b can be arranged as separate elements.

In the construction shown in Fig. 20, the sections 16a and 16b, which expose and close the opening 9 and 15, respectively, are shown as separate elements and are pivotally mounted on the upper part of the frame of the cleaning device 14 and are each pressed in the closing direction by a spring (not shown) with a constant force.

An arcuate joint 33 arranged on the second cover element 16b and produced together with it serves as a movement device for the first cover element 16a. When the second cover element 16b is pivoted back to expose the transmission opening, the joint 33 moves together with this, presses the first cover element 16a downwards and exposes the exposure opening; when the second cover element 16b pivots into the starting position, the joint 33 releases the first cover element 16a, whereby this also returns to the starting position.

The described construction makes it possible to reliably couple the movement of the first cover element 16a with that of the second cover element 16b without having to use a complicated mechanism.

Also in the construction shown in Fig. 20, the second cover element 16b is shaped so that its arms 16d do not protrude beyond the end faces of the cartridge frame and this itself forms the air channel for dissipating the heat generated by the fixing device 5. With this embodiment, the same effects as with the first embodiment can be expected.

(Other ways of inserting and removing the process cartridge)

In the first embodiment, the removal of the process cartridge B from the image forming apparatus A is facilitated in that the frame of the cleaning device 14 is provided with the first projection 24 and the second projection 25 on each end face and the knob 26 above the connecting line between the two projections and when the knob 26 is pulled, the process cartridge is pivoted about the second projections and thereby the first projections 24 slide out of the respective recess 20b (Fig. 14).

However, if the process cartridge B is to be removed, the connection between the first projections 24 and the respective recess 20b can be released by The operator holds the cartridge frame and not the knob 26 and pivots the cartridge B around the second projections.

In other words, the process cartridge B can be removed even without the presence of a knob 26, because all that is required is to pivot the cartridge about the second projections 25.

A further embodiment of the process cartridge B is described below.

Fig. 21 shows the sectional view of another embodiment of the process cartridge B. Fig. 22 (a) shows the left side view and Fig. 22 (b) the right side view of the frame of the cleaning device 14 belonging to the process cartridge B. Fig. 23 shows an example of the insertion of the process cartridge B according to the present invention into an electrophotographic image forming apparatus and the removal of the same therefrom. Fig. 24 shows the side view of the process cartridge during insertion and Fig. 25 shows the side view of the same during removal. Elements which have the same function as those of the first embodiment are identified by the same reference numerals in order to avoid repetition in the description. In this embodiment, however, a toner stirring element 10a5 is arranged in the process cartridge.

As shown in Fig. 22, the process cartridge of this embodiment comprises a left frame member 14c (first frame member, Fig. 22(a)) and a right frame member 14d (second frame member, Fig. 22(b)) as viewed in the axial direction of the photosensitive drum 7. The first frame member 14c is provided with a first projection 24a or (24) and a second projection 25a or (25) which extend outward. The frame member 14d is provided with a third projection 24b or (24) and a fourth projection 25b or (25). (25) which also extend outward. The first and third projections fix the process cartridge B in the main assembly of the apparatus A, while the second and fourth projections serve as pivot members when the process cartridge B is inserted into and removed from the main assembly of the apparatus A. The first and third projections (projection 24) extend directly in the axial direction of the photosensitive drum 7, more specifically, both are cylindrical members and are arranged coaxially about the axis of the photosensitive drum 7. As shown in Fig. 22(a), an axis 7c supporting the photosensitive drum 7 on the left frame member 14c extends beyond the first cylindrical projection 24a, which contacts an electrically conductive member (a leaf spring 50 shown in Figs. 23(a)-23(c)) when the process cartridge B is inserted into the main assembly of the apparatus A, thereby grounding the photosensitive drum 7. In Fig. 22(b), the alphanumeric reference numeral 7d denotes a metal sleeve supporting the photosensitive drum 7 on the right frame member 14d. A fifth projection 14c1 is arranged on the frame member 14c and a sixth projection 14d1 is arranged on the frame member 14d, which also extend outward. The fifth projection 14c1 forms a bridge between the periphery of the first cylindrical projection 24a and that of the second cylindrical projection 25a, and the sixth projection 14d1 forms a bridge between the periphery of the third cylindrical projection 24b and that of the fourth cylindrical projection 25b. The fifth and sixth projections 14c1 and 14d1 serve to prevent excessive swinging of the process cartridge B when the operator erroneously removes his hand from the knob 26 immediately after starting to insert the process cartridge B into the main assembly of the apparatus A or immediately before finishing removing the process cartridge therefrom (the state shown in Fig. 16). When the process cartridge B as shown in Fig. 21 and thereby the photosensitive drum 7 is directed downward, the second cylindrical projection 25a is located above the first cylindrical projection 24a, the fourth cylindrical projection 25b is located above the third cylindrical projection 24b, that is, viewed in the cartridge insertion direction, the second cylindrical projection 25a is located in front of the first cylindrical projection 24a and also the fourth cylindrical projection 25b is located in front of the third cylindrical projection 24b. The first cylindrical projection 24a and the third cylindrical projection 24b have the same outer diameter, while the outer diameter of the second cylindrical projection 25a is larger than that of the first cylindrical projection 24a (and also larger than that of the third cylindrical projection 24b) and the outer diameter of the fourth cylindrical projection 25b is larger than that of the second cylindrical projection 25b. By using cylindrical projections of different sizes, the so-called three-point support of the process cartridge B in the main assembly of the apparatus A can be realized (state shown in Figs. 14 and 23c), which improves the positioning accuracy of the cartridge in the apparatus. In this embodiment, the outer diameter of the first and third cylindrical projections 24a and 24b is about 12 mm (tolerance range 11.0 to 12.5 mm), the outer diameter of the second cylindrical projection 25a is about 12.5 mm (tolerance range 12.0 to 13.5 mm), and that of the fourth cylindrical projection 25b is about 13.0 mm (tolerance range 12.5 to 13.5 mm). The height of the first and second cylindrical projections 24a and 25a is approximately 4.5 mm (tolerance range 1.0 to 5.5 mm) and that of the third and fourth cylindrical projections is approximately 4.0 mm (tolerance range 1.0 to 5.5 mm). The height of the fifth projection 14c1 is approximately 3.0 mm (tolerance range 0.0 to 5.5 mm) and that of the sixth projection 14d1 is approximately 2.5 mm (tolerance range 0.0 to 5.0 mm). It should be noted that the fifth and sixth projections 14c1 and 14d1 are not absolutely necessary. The distance L between the center of the first cylindrical projection 24a and that of the second cylindrical projection 25a or between the center of the third and that of the fourth cylindrical projection 24b and 25b is about 34 mm. The frame of the cleaning device 14 with the left (first) frame section 14c and the right (second) frame section 14d as integral parts thereof accommodates the photosensitive drum 7, the charging device (e.g. the charging roller 8) and the cleaning device (e.g. the elastic blade 11a), and the frame of the developing device 40 (second cartridge frame) accommodates the developing device (e.g. the developing roller 10c) and the toner storage section (e.g. the toner chamber 12b). The frame of the cleaning device 14 and the frame of the developing device 40 are pivotably joined together. The alphanumeric reference numeral 14a1 designates a groove into which the projection 16e engages.

The steps for inserting the process cartridge B into the main assembly of the device A or for removing the cartridge from it are described in detail below in conjunction with Figs. 23(a) to 23(c).

As in the first embodiment, the first projection 24 (24a and 24b) and the second projection 25 (25a and 25b) are pushed into the respective guide groove 20a and guided along it. When the process cartridge B reaches the lowest point, the first projection 24 (24a and 24b) slides into the positioning recess 20b and thereby positions the cartridge in the device. In this state, the second projection 25 (25a and 25b) remains in the guide groove 20a and thereby ensures that the cartridge orientation is maintained in the device. In this state, the process cartridge B this embodiment achieves the so-called three-point support and thus a more precise fixing of the cartridge in the device. In this embodiment, the first projection 24 (24a and 24b) extending directly in the axial direction of the photosensitive drum 7 slides into the recess 20b and remains resting therein by direct pressure. More precisely, a torsion spring 20d arranged on a pin 20c on the guide 20 exerts this pressure, as shown in Fig. 23. One leg of this spring 20d presses against a stop 20i and the other against a stop 21j and a section of the torsion spring 20d projects into the space above the recess 20b. With such an arrangement, when the process cartridge B is inserted along the guide groove 20a in the guide 20, the state shown in Fig. 23(a) is obtained, ie, the corresponding leg of the spring 20d presses against the stopper 20j; as the process cartridge B is further inserted, the first projection 24 (24a and 24b) contacts the torsion spring 20d, lifts the leg from the stopper 20j and is pressed downward by the force generated thereby, as shown in Fig. 23(b). The first projection 24 (24a and 24b) finally slides into the positioning recess 20b, whereby the insertion process is completed. In this state, the spring 20d constantly presses the first projection 24 against the stopper portion 20b1 of the positioning recess 20b, thereby positioning the process cartridge B in the apparatus A, as shown in Fig. 23(c).

As already described, the first projection 24 (24a and 24b) extending directly in the axial direction of the photosensitive drum 7 is constantly pressed downwards by the spring 20d and the photosensitive drum 7 is thereby positioned more precisely in the device A.

In the following, in connection with Fig. 24, the moment is described which acts on the first projection 24 (24a and 24b) and presses it into the recess 20b.

When the operator grasps the cartridge by the knob 26 and pushes it with a force P through an opening 20e in the direction of the positioning section 20b (diagonally downwards), the first projection 24 (24a and 24b) and the second projection 25 (25a and 25b) slide along the cartridge guide 20 until the first projection 24 reaches the lowest point 20a1 of the guide groove 20a above the positioning section 20b. Due to the component Py of the force P now acting on the first projection 24, the process cartridge B begins to pivot about the second projection. The first projection 24 slides into the positioning section 20b and the insertion of the process cartridge B is completed.

The moment acting when removing the process cartridge B is described below in conjunction with Fig. 25. When removing the process cartridge B from the main assembly, the steps shown in Fig. 23 are carried out in the order of 23(c), 23(b), 23(a).

When the operator grasps the knob 26 and pulls the process cartridge with a force P toward the opening 20e (diagonally upward), the component Px of the force P generates a moment about the second projection 25 (25a and 25b), which acts on the first projection 24 (24a and 24b). As a result, the first projection 24 is pushed upward out of the positioning section 20b. That is, the process cartridge B is pivoted counterclockwise about the second projection. When the operator continues to pull the knob 26, the first and second projections slide along the cartridge guide. 20a to completely remove the process cartridge B from the device A.

In this embodiment, a portion 20i is provided on the top of the guide member 20, which extends diagonally upward with respect to the cartridge insertion direction. The projection 16e provided on the arm 16d of the cover 16 comes into contact with this portion 20i. More specifically, when the process cartridge B is inserted into the main assembly of the device A along the guide groove 20a, the projection 16e comes into contact with the portion 20i and is pushed upward. At this time, the cover 16 pivots clockwise against the force of a spring not shown in Fig. 23 and exposes the transfer opening 15 and the exposure opening 9. When the process cartridge B is removed, the spring presses the projection 16e on the cover 16 against the inclined surface of the section 20i, causing the cover to pivot counterclockwise and close the transfer opening 15 and the exposure opening 9.

In this embodiment, the first cylindrical projection 24, the second cylindrical projection 25a and the fifth projection 14c1 are integral parts of the left frame portion 14c, the third cylindrical projection 24b, the fourth cylindrical projection 25b and the sixth projection 14d1 are integral parts of the right frame portion 14d. In other words, the cylindrical projections 24a, 24b, 25a and 25b and the projections 14c1 and 14d1 are integral parts of the frame of the cleaning device 14. This frame is made of a plastic material such as high impact styrene.

(Other embodiments of relevant components)

The present invention is suitable not only for the described process cartridge B which is used for forming a single-color image, but also for a multi-color process cartridge which is used for forming a multi-color image (two-color, three-color or full-color image) and has two or more developing devices.

The developing method according to the present invention is compatible with other known methods such as dual component magnetic brush developing, cascade developing, contact developing, haze developing, etc.

The present invention is not limited to the photosensitive drum as the image bearing member, but can be applied to other areas. For example, when a photoconductive material including amorphous silicon, amorphous selenium, zinc oxide, an organic photoconductor and the like is used as the photosensitive material. In addition, when a rotary member in the form of a drum, a belt or the like is used as the base member on which the photosensitive material is applied, a drum or a belt is generally used as the base member. In the case of a drum, the photoconductive material is applied to a cylinder made of an aluminum alloy or the like by coating, deposition or other means.

The charging device used in the first embodiment operates on the principle of touch charging, but it goes without saying that the present invention can be applied to other conventional charging methods. can be used, for example, in which a screen made of aluminium or another metal is arranged on three sides of a tungsten electrode, a high voltage is applied to the tungsten electrode to generate positive or negative ions, transfer them to the surface of the photosensitive drum and charge the drum uniformly.

The charging device described is a roller charging device, but instead of this a charging device can also be used in which the charge is transferred using a charging blade, a charging pad, a charging block, a charging rod or wire or another element.

A device that uses a blade, a fur brush, a magnetic brush or another element to remove residual toner from the photosensitive drum can be used as a cleaning device.

The described process cartridge comprises an electrophotographic photosensitive member and at least one processing device. In other words, the present invention can be applied not only to the process cartridge used in the described embodiments, but also to a process cartridge of another type. This includes a process cartridge which comprises either an image bearing member and a charging device, an image bearing member and a developing device, an image bearing member and a cleaning device, or an image bearing member and two or more of the above-mentioned processing devices and can be interchangeably inserted into an image forming apparatus.

In other words, the process cartridge described is a cartridge in which a charging device, a developing device or a cleaning device together with an electrophotographic photosensitive element or at least one developing device together with an electrophotographic photosensitive element are accommodated therein and which is designed as a replacement cartridge.

The description of the various embodiments was made in connection with a laser printer as an image forming device. However, the present invention is not limited to a laser printer, but can also be applied to other image forming devices, for example an electrophotographic copier, fax machine or word processor.

The process cartridge contains the electrophotographic photosensitive member, the developing device or other processing device and can produce very precise images.

Accordingly, high-quality images can be recorded more stably in electrophotographic copiers, laser beam printers or other devices using the process cartridge according to the present invention.

In the described embodiments of the present invention, the first projection is arranged directly in the axial direction of the electrophotographic photosensitive member, while the second projection serves as a cartridge pivoting member. That is, these projections serve not only as guide members when inserting the process cartridge into the image forming apparatus and when removing the cartridge therefrom, because when removing the process cartridge from the apparatus main assembly it can be easily pivoted around the second projection to lift the first projection resting in the positioning recess on the main assembly of the device. In this way, the process cartridge can be easily pulled out of the device.

Regarding the cartridge insertion direction, the second projection is located behind the first projection and the knob is located above the connecting line between the first and second projections, whereby the operator only has to pull the knob to lift the first projection out of the positioning recess and pull the cartridge out of the device.

The cartridge guide is arranged diagonally downwards in the image forming device so that the operator only has to grasp the cartridge knob to insert or remove the process cartridge from the device.

The first and second projections and the knob are arranged on the frame equipped with the electrophotographic photosensitive drum so that the cartridge can be easily pivoted about the second projection.

The process cartridge has a frame provided with the projections and the knob in which an electrophotographic photosensitive member, a developing device and other elements are arranged so that high-quality images can be stably produced with electrophotographic copiers, laser printers or similar devices in which such a process cartridge can be used.

As already described, the present invention provides a process cartridge and a device equipped with this cartridge. imaging device to facilitate the insertion and removal of the cartridge.

Claims (19)

1. A process cartridge (B) which can be installed and removed from a main assembly (A) of an image forming apparatus, comprising: an electrophotographic photosensitive member (7) having first and second axial ends; a processing device (8, 10) which can act on the light-sensitive element (7); a first projection (24a) for positioning the process cartridge (B) with respect to the main assembly (A) when the process cartridge is installed in the main assembly, the first projection (24a) protruding outwardly from a first frame portion (14c) adjacent to the first axial end of the photosensitive member (7); a second projection (25a) serving as a fulcrum when the process cartridge is removed from the main assembly, the second projection (25a) projecting outward from the first frame portion (14c); a third projection (24b) for positioning the process cartridge with respect to the main assembly when the process cartridge is installed in the main assembly, the third projection protruding outwardly from a second frame portion (14d) adjacent to the second axial end of the photosensitive member (7); a fourth projection (25b) serving as a fulcrum when the process cartridge is removed from the main assembly, the fourth projection projecting outward from the second frame portion (14d), marked by a handle (26) located above a line connecting the center of the first projection (24a) and the center of the second projection when the first frame portion is viewed from one of the axial end sides of the photosensitive member, the handle causing the positioning action of the first and third projections (24a, 24b) to be released by rotation of the process cartridge (B) about an axis defined by the second and fourth projections (25a, 25b) when the handle (26) receives a force in the direction in which the process cartridge (B) is removed from the main assembly (A). 2. Process cartridge (B) according to claim 1, wherein the first and second frame sections (14a, 14b) form a unit. 3. Process cartridge (B) according to claim 1 or 2, wherein the first to fourth projections (24a, 25a, 24b, 25b) are substantially cylindrical. 4. Process cartridge (B) according to one of the preceding claims, wherein the first and third projections (24a, 24b) are coaxial. 5. A process cartridge according to claim 4, wherein the first (24a) and third (24b) projections are coaxial with the photosensitive member (7) which has the shape of a drum. 6. Process cartridge (B) according to one of the preceding claims, wherein the first to fourth projections (24a, 25a, 24b, 25b) are cylindrical and the first cylindrical projection (24a) and the third cylindrical projection (25a) have substantially the same diameter, the second cylindrical projection (25a) has a larger diameter than the first (24a) and third (25a) cylindrical projection and the fourth cylindrical projection (25b) has a larger diameter than the second cylindrical projection (25a). 7. A process cartridge according to claim 6, wherein the outer diameter of the first projection (24a) and the third projection (24b) is 12 mm, the diameter of the second projection (25a) is 12.5 mm and the diameter of the fourth projection (25b) is 13.0 mm. 8. A process cartridge according to any preceding claim, wherein the first projection (24a) and the third projection (24b) are round members coaxial with a shaft (7c, 7d) for supporting the photosensitive member (7). 9. Process cartridge according to claim 8, wherein the shaft (7c, 7d) is made of metal and the round elements (24a, 24b) are made of plastic resin material. 10. The process cartridge according to claim 9, wherein the round member serving as the first projection (24a) is formed integrally with the first frame portion (14c) and the round member serving as the third projection (24b) is formed integrally with the second frame portion (14d). 11. A process cartridge according to claim 8, wherein the shaft (7c) protrudes from the round member serving as the first projection (24a) and can be brought into contact with an electrically conductive member (50) in the main assembly (A) when the process cartridge (B) is installed in the main assembly (A). 12. Process cartridge according to claim 1, with a fifth A projection (14ac1) which is elongated and projects outwardly from the first frame portion (14c), the fifth projection (14c1) connecting the first projection (24a) and second projection (25a), and a sixth projection (14d1) which is elongated and projects outwardly from the second frame portion (14d), the sixth projection (14d1) connecting the third projection (24b) and fourth projection (25b). 13. A process cartridge according to claim 12, wherein the first projection (24a) and second projection (25a) are round and the fifth projection (14c1) extends between their outer circumferences and wherein the third projection (25a) and fourth projection (25b) are round and the sixth projection (14d1) extends between their outer circumferences. 14. A process cartridge according to claim 13, wherein the first projection (24a), second projection (25a) and fifth projection (14c1) are formed integrally with the first frame portion (14c), and the third projection (24b), fourth projection (25b) and sixth projection (14d1) are formed integrally with the second frame portion (14d). 15. A process cartridge according to any preceding claim, wherein the cartridge is shaped such that its dimension in the direction generally parallel to the axial direction of the photosensitive member is larger than its dimension in the direction transverse to the axial direction. 16. Process cartridge according to one of the preceding claims, in which the process device comprises a charging device (8) for charging the photosensitive element, a cleaning device (11) for removing residual toner from the photosensitive element (7) and/or a developing device (10) for developing a latent image formed on the photosensitive element (7). 17. Process cartridge according to one of the preceding claims, wherein a first cartridge frame (14) contains the photosensitive member (7), a charging device (8) for charging the photosensitive member and a cleaning device (11) for removing residual toner from the photosensitive member (7), and a second cartridge frame (12) contains a developing device (10) for developing a latent image formed on the photosensitive member (7) and a toner containing section (10a, 12b) for containing toner to be used by the developing device (10), the first cartridge frame and the second cartridge frame being swingable relative to each other. 18. A combination of a process cartridge (B) according to claim 1 and an image forming device (A) for forming an image on a recording material, wherein the process cartridge can be installed in the image forming device by insertion in an insertion direction and can be removed therefrom in a removal direction opposite to the insertion direction and wherein the image forming device (A) comprises: an installation device for installing and removing the process cartridge into a main body of the image forming apparatus, the installation device comprising first and second guide devices, each having: a first positioning means (20a) for positioning the second or fourth projection (25a, 25b) with respect to the installation device; and a second positioning means (20b, 20b1) for positioning the first or third projection (24a, 24b) with respect to the installation device, the arrangement being such that when the second and fourth projections of the cartridge are engaged with their respective first positioning means, pivotal movement of the process cartridge (B) in a first rotational direction about the second and fourth projections results in the handle (26) moving in the insertion direction and the first and third projections being engaged with their respective second positioning means, and pivotal movement of the process cartridge in a second rotational direction opposite to the first rotational direction results in the handle moving in the removal direction and the first and third projections being disengaged from their respective second positioning means. 19. An image forming apparatus to be used in the combination according to claim 18, wherein the installation means includes the first guide means (20a, 20b, 20b1) for guiding the first projection and the second projection and the second guide means (20a, 20b, 20b1) for guiding the third projection and the fourth projection, and the second positioning means of the first guide means comprises a first recess (20b) communicating with the first positioning means of the first guide means and a spring (20d) for urging the first projection (24a) into the first recess, and the second positioning means of the second guide means comprises a second recess (20b) communicating with the first positioning means (20a) of the second guide means and a spring (20d) for urging the third projection (24b) into the second recess.